Achieving accurate mark positioning (print registration) on a shrink wrapping machine ensures that your logos and graphics appear in the exact same spot on every package, rather than drifting or getting cut off.



This process requires coordination between your machine's photo eye sensor and the registration marks (eye marks) printed on your film.



1. Prerequisites

Before attempting setup, ensure you have the following:

  • Registered Film: Your shrink film must have a "registration mark" or "eye mark" (usually a small black block) printed on the edge of the film at regular intervals for every bag length.

  • Photo Eye Sensor: Your machine must be equipped with a print registration sensor (fiber optic or standard photo eye) capable of detecting contrast changes.

2. Step-by-Step Setup Guide

Step 1: Thread the Film

Thread the printed film through the machine's rollers and forming plow as you normally would. Ensure the film is under proper tension. If the film is loose, the sensor will misread the marks.

Step 2: Enable "Print Registration" Mode

On your machine’s HMI (touchscreen) or control panel, look for a setting labeled "Print Registration," "Eye Mark," "Photo Eye," or "Color Code."

  • Turn this setting ON.

  • This tells the machine to stop cutting based on time or length alone and instead wait for the sensor's signal to trigger the seal/cut.

Step 3: Physical Sensor Alignment

Locate the photo eye sensor along the film path (usually near the film infeed or just before the forming plow).

  • Manually pull the film until an eye mark is directly in front of the sensor.

  • Adjust the sensor physically (slide it left or right) so the light beam hits the center of the eye mark track.

Step 4: "Teach" the Sensor

Most modern sensors need to be "taught" to recognize the contrast between the dark mark and the clear/colored background film.

  1. Background Set: Place the light spot on the background (the area without the mark) and press the "Teach" or "Set" button.

  2. Mark Set: Move the film so the light spot is on the black eye mark and press the "Teach" or "Set" button again.

  3. Verification: Move the film back and forth. The sensor's indicator light should flash only when the mark passes under it.

Step 5: Input Bag Length

Enter the Bag Length on your machine's interface.

  • Crucial Tip: When using print registration, set the machine's bag length setting to be slightly longer (2-5mm) than the actual distance between eye marks.

  • Why? This ensures the machine is always "looking" for the mark just before it expects the bag to end. If the set length is shorter than the physical mark distance, the machine will cut before it ever sees the mark.

Step 6: Adjust Cut Position (Offset/Delay)

Run a test pack. The machine will likely cut the bag, but the image might be too high or too low on the product.

  • Find the "Cut Position," "Offset," or "Delay" setting in the menu.

  • If the cut is too early (cutting into the logo): Increase the delay/offset value.

  • If the cut is too late: Decrease the value.

  • Continue adjusting this value in small increments until the seal aligns perfectly between the graphics.